Method and apparatus for irradiating simulated solar radiation

ABSTRACT

In a method of irradiating an object with simulated solar radiation using a plurality of light sources, the object is irradiated with simulated solar radiation resulting from superimposed light rays from a plurality of light sources including light sources having different times at which light emission output reaches a peak.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for irradiatingan object with temporally stable light, and more particularly, to amethod and apparatus for irradiating simulated solar radiation, whichneeds to be irradiated in large light quantity and over a large area, intemporally stable light quantity and spectrum. The present inventionalso relates to a method and apparatus for irradiating a semiconductordevice which is an object temporally responding relatively quickly to atemporal variation in light quantity over a sensitive wavelength rangewith temporally stable light.

2. Related Background Art

As a method for irradiating a semiconductor device with simulated solarradiation, Japanese Patent Application Laid-Open No. S61-269801discloses a method of lighting and irradiation using a xenon lamp as alight source, using an expensive air mass filter for adjusting aspectral distribution and using an expensive stabilized DC power supplyas a power supply source. Though this method is costly, it can securetemporal stability of light quantity relatively easily and isappropriate for a case where an object to be irradiated is small and thetotal price falls within an allowable range. However, the price of thismethod increases at an accelerating pace as the required irradiationarea grows. This is because attempting to irradiate the entire surfaceof an object with substantially uniform light in response to an increaseof the area of the object requires increases in size of components suchas the air mass filter and other optical systems, which increases thedegree of difficulty of manufacturing in an accelerating pace andfurther requires an increase in the capacity of the expensive stabilizedDC power supply for the lamp, which is costly from the very beginning.

As one of methods for realizing a large area, Japanese PatentApplication Laid-Open No. H11-26785 discloses a method for lighting alamp using pulses. This method is effective in terms of reducing thecapacity of a power supply for the lamp. However, the necessity forlarge size components such as an air mass filter and other opticalsystems remains the same and this method is still costly. Moreover,while this method takes into account the temporal stability of lightquantity during a pulse lighting-up time, it ignores the temporalstability of continuous light quantity including a non-lighting-up time.

SUMMARY OF THE INVENTION

As described above, according to the conventional technologies, when anattempt is made to irradiate an object with temporally stable light, theprice of the apparatus increases as the light quantity and the areaincrease or such temporal stability must be unavoidably ignored, all ofwhich make the method difficult to realize in practice.

It is an object of the present invention to provide a method andapparatus for irradiating an object with temporally stable light at lowcost and using actually feasible means. More specifically, it is anobject of the present invention to provide a method and apparatus forirradiating simulated solar radiation, which needs to be irradiated inlarge light quantity and over a large area, with temporally stable lightquantity and spectrum. It is another object of the present invention toprovide a method and apparatus for irradiating a semiconductor devicewhich is an object responding relatively quickly to a temporal variationin light quantities over a sensitive wavelength range, with temporallystable light.

In order to attain the above-described objects, a method and apparatusfor irradiating light according to the present invention ischaracterized by irradiating an object with simulated solar radiationresulting from superimposed light rays from a plurality of light sourcesincluding light sources having different times at which light emissionoutput reaches a peak.

Furthermore, a light irradiation apparatus used for a characteristictest of a semiconductor device of the present invention is characterizedin that an object is irradiated with light resulting from superimposedlight rays from a plurality of light sources including light sourceshaving different times at which light emission output reaches a peak.

Furthermore, a method of testing characteristics of a semiconductordevice with a light irradiating step of the present invention ischaracterized by including a step of irradiating a semiconductor devicewith light resulting from superimposed light rays from a plurality oflight sources including light sources having different times at whichlight emission output reaches a peak.

The light sources having different times at which light emission outputreaches a peak are preferably light sources having a plurality oflight-emitting seeds with different time constants.

The light sources having different times at which light emission outputreaches a peak are preferably discharge lamps and more preferablymercury lamps or metal halide lamps.

The output waveforms of the light sources having different times atwhich light emission output reaches a peak are preferably substantiallysimilar or substantially periodic.

The energy supply sources of the light sources having different times atwhich light emission output reaches a peak are preferably single-phaseAC, two-phase AC or three-phase AC.

The phase difference of light emission output peaks of the light sourceshaving different times at which light emission output reaches a peak ispreferably an integer multiple of 1/n of 180 degrees, where n is thenumber of light sources or the number of light source groups havingdifferent times at which light emission output reaches a peak.

The arrangement of the light sources having different times at whichlight emission output reaches a peak preferably includes an arrangementof m-gon, where m is an integer multiple of n and n is the number oflight sources or the number of light source groups having differenttimes at which light emission output reaches a peak. A lineararrangement is also preferable.

The arrangement of the light sources having different times at whichlight emission output reaches a peak is preferably set in such a waythat when the number of light sources or the number of light sourcegroups having different times at which light emission output reaches apeak is 2, the ratio of a sum total of irradiation light quantities oflight sources or light source groups having different times at which onelight emission output reaches a peak to a sum total of irradiation lightquantities of light sources or light source groups having differenttimes at which other light emission outputs reach a peak is 0.82 to 1.22as a standard for an object to be irradiated.

Furthermore, the arrangement of the light sources having different timesat which light emission output reaches a peak is preferably set in sucha way that when the number of light sources or the number of lightsource groups having different times at which light emission outputreaches a peak is 3, the ratio of a sum total of irradiation lightquantities of light sources or light source groups having differenttimes at which one light emission output reaches a peak to a sum totalof irradiation light quantities of light sources or light source groupshaving different times at which other light emission outputs reach apeak is 1:0.75 to 1.33 as a standard for an object to be irradiated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a method and apparatus for irradiatinglight according to first embodiment of the present invention;

FIG. 2 is a graph showing a relationship between irradiation lightquantity acquired at the position of an object to be irradiatedaccording to first and second embodiments of the present invention andtime;

FIG. 3 is a schematic view of a method and apparatus for irradiatinglight according to second embodiment of the present invention;

FIG. 4 is a schematic view of a method and apparatus for irradiatinglight according to third embodiment of the present invention;

FIG. 5 is a schematic view of the method and apparatus for irradiatinglight according to third embodiment of the present invention;

FIG. 6 is a graph showing a relationship between irradiation lightquantity acquired at the position of an object to be irradiatedaccording to third embodiment of the present invention and time;

FIG. 7 is a schematic view of a method and apparatus for irradiatinglight according to fourth embodiment of the present invention;

FIG. 8 is a schematic view of the method and apparatus for irradiatinglight according to fourth embodiment of the present invention;

FIG. 9 is a graph showing a relationship between irradiation lightquantity acquired at the positions right below a projector 4 a and alamp 5 a according to fourth embodiment of the present invention andtime;

FIG. 10 is a schematic view of a method and apparatus for irradiatinglight according to fifth embodiment of the present invention;

FIG. 11 is a schematic view of the method and apparatus for irradiatinglight according to fifth embodiment of the present invention;

FIG. 12 is a graph showing a relationship between irradiation lightquantity acquired at the positions right below a projector 4 a and alamp 5 a according to fifth embodiment of the present invention andtime;

FIG. 13 is a schematic view of a method and apparatus for irradiatinglight according to sixth embodiment of the present invention;

FIG. 14 is a schematic view of a method and apparatus for irradiatinglight according to comparative example 1; and

FIG. 15 is a graph showing a relationship between irradiation lightquantity acquired at the position of an object to be irradiatedaccording to comparative example 1 and time.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be explained below,but the present invention is not limited to these embodiments.

<Optical System>

With regard to a light source, on the premise that a plurality of lightsources are used, it is possible to select various types of lightsources in consideration of the light quantity required, irradiationarea required and spectral distribution required, etc. According to thepresent invention, it is possible to use a light source which, when litwith an AC through an igniter, has excellent temporal responsivity to apower supply variation with its light emission output sensitivelyvarying in a cycle double the AC frequency because it is lit with an AC.For example, it is also possible to use a discharge lamp like a mercurylamp which can easily obtain large light quantity. Furthermore, it isalso preferable to use a metal halide lamp, etc., which can easilyobtain large light quantity and for which a spectral distribution isalso currently being improved. Furthermore, according to the presentinvention, a light source having a plurality of light-emitting seedswith different time constants such as a metal halide lamp can securenecessary temporal stability in a spectral distribution, and istherefore a preferable light source. Here, a “time constant of alight-emitting seed” in this Specification means a time required toattenuate from peak intensity to a value of certain percentage (e.g.,1/e of peak intensity).

It is possible to use various optical parts such as condenser,reflector, integrator, collimator lens, spectral correction filter,diffusing filter, light-shielding plate as required for the opticalsystem. Furthermore, it is also preferable to use an optical unit suchas a projector whose upsizing is relatively easy to incorporate theabove-described plurality of light sources in one unit.

<Energy Supply System>

Various types of energy can be used for the energy supply system. For astable power supply, it is preferable to supply power supplied from apower company as a primary side AC power supply of the equipment.Furthermore, it is also preferable to supply power through a powergenerator using various types of fuel such as petroleum and gas becausea two-phase AC can be easily supplied in this way. Moreover, DC powercan also be supplied from a battery, etc.

Using an AC power supply such as single-phase AC, two-phase AC,three-phase AC to supply energy is preferable because it is possible tosupply substantially similar, substantially periodic energy in this way.It is also preferable to provide a mechanism which temporally shiftslight emission output peaks of a light source at some part of an energysupply route as required. Two-phase AC and three-phase AC are preferablebecause they have components with different phases from the beginning.

Furthermore, it is also possible to supply energy in a pulsated form bytemporarily storing charge in a capacitor.

<Light Emission Output>

Various light emission outputs can be obtained by combining varioustypes of light source, optical system and energy supply system. Then, itis possible to irradiate an object with temporally stable light bysuperimposing light rays from light sources having different times atwhich light emission output reaches a peak. As light emission output tobe focused, it is possible to set light quantity in an entire wavelengthrange, light quantity for each predetermined wavelength range defined bya standard, etc., light quantity in a wavelength range havingsensitivity to an object to be irradiated, etc., depending on thepurpose of use of this method and apparatus for irradiating light asappropriate.

Output waveforms of light sources having different times at which lightemission output reaches a peak are preferably substantially similar whenconsideration is given to ease of control. It is also preferablysubstantially periodic. Such waveforms are preferable because they canbe obtained easily by selecting, for example, AC power as the energysupply system and combining light sources whose light emission output isalso sensitively variable in a cycle double an AC frequency because theyare lit with an AC as the light sources.

Various levels of the temporal stability of light quantity irradiatedwith light resulting from superimposed light rays from light sourceshaving different times at which light emission output reaches a peak areselected according to the purpose of use. For example, with regard to asolar simulator (simulated solar radiation irradiation apparatus for aphotovoltaic device) used for testing a photovoltaic device, IEC60904-9describes the required performance of spectral coincidence to besatisfied in the area used of the surface to be irradiated, in-planevariation of irradiance and temporal stability. With regard to thetemporal stability, class A is within ±2%, class B is within ±5% andclass C is within ±10%. To be qualified as having passed a testverifying the required performance in compliance with IEC60904-9, it isnecessary to use a light irradiation apparatus that satisfies theperformance also in the aspect of temporal stability of light quantity.

Thus, the temporal stability of light quantity irradiated to an objectis preferably within ±10%.

At this time, in order to irradiate the object to be irradiated withlight in temporally stable light quantity, it is possible to set anarrangement of a plurality of light sources by trial and error, but itis preferable that an appropriate arrangement standard be made settablebecause this can reduce the total adjustment load drastically. Avariation of light emission output can be divided into a ground lightemission component as a minimum value of light emission output and avariable component added thereto. As opposed to a case of responding toa variation of energy with which the light emission output whose groundlight emission component is substantially 0 is supplied moresensitively, the ratio of the variation width of light emission outputto average light emission output is improved by the effect of the groundlight emission component and decreases as the ground light emissioncomponent increases. In other words, when attention is focused on theground light emission component, it is possible to set a moreappropriate standard by estimating the light emission output whoseground light emission component is substantially 0 as a basis.

Furthermore, various levels of temporal stability of a spectraldistribution irradiated with light resulting from superimposed lightrays from light sources having different times at which light emissionoutput reaches a peak can also be selected depending on the purpose ofuse thereof. With regard to spectral coincidence set for eachpredetermined wavelength range in aforementioned IEC60904-9, class A iswithin a range of 0.75 to 1.25, class B is within a range of 0.6 to 1.4and class C is within a range of 0.4 to 2.0. To be qualified as havingpassed a test verifying the required performance in compliance withIEC60904-9, it is necessary to use a light irradiation apparatus thatsatisfies the performance also in the aspect of temporal stability inspectral coincidence.

Thus, the temporal stability of spectral coincidence irradiated to anobject is preferably within a range of 0.4 to 2.0.

At this time, when attention is focused on a spectral distribution, alight source having a plurality of light-emitting seeds with differenttime constants, in response to a variation of energy with which thelight emission output of a light-emitting seed whose time constant issubstantially 0 is supplied more sensitively, the variation width of thelight emission output is improved by the temporal averaging effect bythe time constant and decreases as the time constant of thelight-emitting seed increases. In other words, when attention is focusedon a difference in the time constant, it is possible to set a moreappropriate standard by estimating the light emission output whose timeconstant is substantially 0 as a basis.

When energy which is the square of a sine wave is supplied from anenergy supply system and light emission output is obtained according tothe energy, that is, when the ground light emission component and timeconstant are regarded as substantially 0, a case where light rays fromtwo light sources having different times at which light emission outputreaches a peak is as shown in the following example.

TABLE 1 0 degree (reference) 1.00 1.00 1.00 1.00 1.00 Amplitude ratio of90 1.00 0.95 0.90 0.85 0.82 degrees Temporal stability of 0 3 5 8 10irradiation light quantity of superimposed light (±%)

The phase of a quasi-sine wave of one light source was set to 0 degreeas a reference and the phase of a quasi-sine wave of the other lightsource was set to 90 degrees. In Table 1, the temporal stability ofirradiation light quantity of superimpose light was checked by changingthe amplitude ratio of the light source with the phase of the quasi-sinewave set to 90 degrees to the light source with the phase of thequasi-sine wave set to 0 degree. That is, the light source with thephase of the quasi-sine wave set to 0 degree and light source with thephase of the quasi-sine wave set to 90 degrees only differ in theamplitude and are substantially similar. To satisfy a range of within±10%, an amplitude ratio up to 0.82 is acceptable. If a reversereference is adopted, an amplitude ratio up to 1.22 is acceptable.

When energy corresponding to the square of the sine wave is suppliedfrom an energy supply system and light emission output is obtainedaccording to the energy, that is, when the ground light emissioncomponent and time constant can be regarded as substantially 0, a casewhere light rays from three light sources having different times atwhich light emission output reaches a peak are superimposed is as shownin the following example.

TABLE 2 0 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 degree (refer-ence) Am- 1.00 1.00 1.00 1.00 0.90 0.90 0.90 0.85 0.75 plitude ratio of120 degrees Am- 1.00 0.90 0.80 0.73 0.90 0.80 0.71 0.71 0.75 plituderatio of 240 degrees Tem- 0 3 7 10 4 6 10 10 10 poral stability of irra-diation light quantity of super- imposed light (±%)

The phase of a quasi-sine wave of one light source was set to 0 degreeas a reference and the phases of quasi-sine waves of the other lightsources were set to 120 degrees and 240 degrees. In Table 2, thetemporal stability of irradiation light quantity of superimpose lightwas checked by changing the amplitude ratio of the light source with thephase of the quasi-sine wave set to 120 degrees and 240 degrees to thelight source with the phase of the quasi-sine wave set to 0 degree. Thatis, the light sources with the phase of the quasi-sine wave set to 0degree, 120 degrees and 240 degrees only differ in the amplitude and aresubstantially similar. To satisfy a range of within ±10%, an amplituderatio up to 0.71 to 0.75 is acceptable. If a reverse reference isadopted, an amplitude ratio up to 1.41 to 1.33 is acceptable.

(Arrangement of Optical System)

Various types of arrangement can be adopted for an optical system. Inorder to superimpose light rays from light sources having differenttimes at which light emission output reaches a peak and obtain desiredtemporal stability efficiently at an object or a surface to beirradiated, it is preferable to adopt an arrangement which prevents thelight sources having different times at which light emission outputreaches a peak from blocking each other's irradiation optical path.

The number of light sources can be set as required. It is possible touse one set of light sources having different times at which lightemission output reaches a peak or form a plurality of light sourceshaving substantially coinciding times at which light emission outputreaches a peak as one group and combine it with a group of light sourceshaving different times at which light emission output reaches a peak orcombine it with a still further light source. It is desirable to set anarrangement of each light source in consideration of the light quantityirradiated from each light source to each irradiation point and thebalance among light quantities irradiated from the respective lightsource groups. It is further preferable to set the arrangement based ona desirable numerical value range when superimposing light rays fromlight sources having different times at which the aforementioned lightemission output reaches a peak.

At this time, an arrangement of the light sources having different timesat which light emission output reaches a peak based on an m-gon, where mis an integer multiple of n and n is the number of light sources or thenumber of light source groups having different times at which lightemission output reaches a peak is preferable because it is easier tobalance light quantities within the area in which the object or surfaceto be irradiated is used. Furthermore, a linear arrangement is alsopreferable because it is easier to balance light quantities.

(Object to be Irradiated)

Various objects can be used as objects to be irradiated. For example, inthe case of a semiconductor device such as a photovoltaic device,responsivity to irradiation light quantity is important and it ispreferable to irradiate temporally stable light according to the purposethereof.

Furthermore, the present invention is preferable because it canirradiate a large-size semiconductor device including a solar cell,solar cell submodule, solar cell module or photovoltaic array, etc.,with temporally stable light. The present invention is preferablebecause it can also irradiate a semiconductor device such as a stackedsolar cell which sensitively responds with a spectral distribution usinglight rays in a wavelength range which varies from one layer to anotherwith light having a temporally stable spectral distribution.

EMBODIMENTS

With reference now to attached drawings, the present invention will beexplained using embodiments described below, but the present inventionis not limited to these embodiments.

Embodiment 1

FIG. 1 is a schematic view of a method and apparatus for irradiatinglight according to first embodiment of the present invention. FIG. 2 isa graph showing a relationship between irradiation light quantityacquired at the position of the object to be irradiated in FIG. 1 andtime. FIG. 14 is a schematic view of a method and apparatus forirradiating light according to comparative example 1 and FIG. 15 is agraph showing a relationship between irradiation light quantity acquiredat the position of the object to be irradiated in FIG. 14 and time.

In Embodiment 1 and comparative example 1, a metal halide lamp which islit with an AC through an igniter was used as a light source. The metalhalide lamp can be lit through an inexpensive igniter, it is growing inlight quantity and its spectral distribution is being improved, and inthis respect the metal halide lamp is a promising simulated solarradiation light source. On the other hand, since it has high temporalresponsivity to power supply variations and because it is lit with anAC, its light emission output also varies sensitively in a cycle doublethe AC frequency and has a plurality of light-emitting seeds withdifferent time constants, thus having the nature that its spectraldistribution also varies temporally.

In comparative example 1 shown in FIG. 14 and FIG. 15, power suppliedfrom a primary side AC power supply of equipment 101 is supplied to alamp 105 in a projector 104 through an electric wiring 102 and anigniter 103. The lamp 105 is lit with an AC and an irradiation lightquantity waveform 109 measured at the position of an object to beirradiated 107 also fluctuates in a cycle double the AC frequency.

On the contrary, in Embodiment 1 shown in FIG. 1 and FIG. 2, an ACsupplied from a primary side AC power supply of equipment 1 is suppliedto lamps 5 a and 5 b in two projectors 4 a and 4 b through electricwirings 2, 2 a and 2 b and igniters 3 a and 3 b. However, the phase ofthe AC supplied to the lamp 5 b is shifted by 90 degrees by a mechanism8 for shifting the phase by 90 degrees as some midpoint of the electricwiring 2 b. The lamps 5 a and 5 b are lit with an AC and irradiationlight quantity waveforms 9 a and 9 b measured at the position of anobject to be irradiated 7 obtained when they are lit singly alsofluctuate in a cycle double the AC frequency. The irradiation lightquantity waveform 9 b has a different phase, but is a waveformsubstantially similar to that of the irradiation light quantity waveform9 a. If the lamps 5 a and 5 b are turned ON simultaneously, since thereis a phase difference of 90 degrees of ACs supplied to the two lamps 5 aand 5 b, an irradiation light quantity waveform 9 with substantially notemporal variation is obtained. This is the same as the case whereattention is focused on the light quantity within a predeterminedwavelength range, and as a result, spectral coincidence withsubstantially no temporal variation is obtained.

In Embodiment 1, the positional relationship between the object to beirradiated 7, two projectors 4 a and 4 b and lamps 5 a and 5 b areassumed to be an equidistant and symmetric positional relationship. Thetwo projectors 4 a and 4 b were tilted toward the object to beirradiated 7. Furthermore, they were arranged so that irradiation lightrays from the respective lamps 5 a and 5 b and projectors 4 a and 4 b tothe object to be irradiated 7 were not blocked by the opposite projectoror lamp or other objects. This makes the temporally averaged lightquantities irradiated from the lamps 5 a and 5 b substantially equalover the entire surface of the object to be irradiated 7 and even if theentire surface of the object to be irradiated 7 is divided into smallerareas and measured, it is possible to obtain the irradiation lightquantity waveform 9 with substantially no temporal variation.

Furthermore, in order to set the temporal stability of irradiation lightquantity of the superimposed light to within ±10%, setting thearrangement of the optical system in such a way that the ratio of theamplitude of the irradiation light quantity waveform 9 a to theamplitude of the irradiation light quantity waveform 9 b measured at theposition of the object to be irradiated 7 when the lamps are lit singlyis set to 1:0.82 to 1.22 as a standard can reduce the total adjustmentload drastically and is therefore preferable.

Using the method and apparatus for irradiating light according toEmbodiment 1, it is possible to measure, for example, the output of asolar cell module which is a semiconductor device showing quick temporalresponse to a temporal variation of light quantity. Since irradiationlight quantity with substantially no temporal variation is obtained,even a solar cell module which shows quick temporal response producesoutput with substantially no temporal variation. Therefore, it ispossible to measure the output of the solar cell modulewithout-specially performing adjustment of measuring timings andaveraging processing of measured values, etc. Furthermore, by changing,for example, the distance between the two lamps 5 a and 5 b and thesolar cell module or increasing the number of projectors and lamps asrequired, it is also possible to change the absolute value ofirradiation light quantity to the solar cell module or measure therelationship between the output of the solar cell module and irradiationlight quantity.

Embodiment 2

FIG. 3 is a schematic view of a method and apparatus for irradiatinglight according to second embodiment of the present invention. FIG. 2 isa graph showing a relationship between the irradiation light quantityobtained at the position of the object to be irradiated in FIG. 3 andtime as in the case of Embodiment 1. This embodiment has a mode of powersupply slightly different from that of Embodiment 1 shown in FIG. 1.

In Embodiment 2 shown in FIG. 3, power supplied from a primary side ACpower supply of equipment 1 is supplied to lamps 5 a and 5 b in twoprojectors 4 a and 4 b through electric wirings 2 a and 2 b and igniters3 a and 3 b. As the primary side AC power supply of equipment 1, athree-phase AC is used here. If the phase of the AC supplied to the lamp5 a is set as a reference (0 degree), the AC supplied to the lamp 5 buses a phase different from the reference phase by 120 degrees and byproviding a mechanism 8 for shifting the phase by 30 degrees at somemidpoint of the electric wiring 2 b, the phase is shifted by a total of90 degrees. The lamps 5 a and 5 b are lit with ACs and irradiation lightquantity waveforms 9 a and 9 b measured at the position of an object tobe irradiated 7 obtained when they are lit singly also fluctuate in acycle double the AC frequency. The irradiation light quantity waveform 9b has a different phase, but it is a waveform substantially similar tothat of the irradiation light quantity waveform 9 a. If the lamps 5 aand 5 b are turned ON simultaneously, since there is a phase differenceof 90 degrees between the ACs supplied to the two lamps 5 a and 5 b, anirradiation light quantity waveform 9 with substantially no temporalvariation is obtained.

When the method and apparatus for irradiating light according to thepresent invention is used as actual equipment, it is also possible toadopt the configuration shown in this embodiment for convenience of theprimary side AC power supply of the equipment, etc.

Embodiment 3

FIG. 4 and FIG. 5 are schematic views of a method and apparatus forirradiating light according to a third embodiment of the presentinvention. FIG. 6 is a graph showing a relationship between theirradiation light quantity obtained at the position of an object to beirradiated in FIG. 4 and time. As in the case of Embodiment 1,Embodiment 3 also uses a metal halide lamp which is lit with an ACthrough an igniter as the light source.

In Embodiment 3 shown in FIG. 4, FIG. 5 and FIG. 6, power supplied froma primary side AC power supply of equipment 1 is supplied to lamps 5 a,5 b and 5 c in three projectors 4 a, 4 b and 4 c through electricwirings 2 a, 2 b and 2 c and igniters 3 a, 3 b and 3 c. As the primaryside AC power supply of equipment 1, a three-phase AC is used here. Ifthe phase of the AC supplied to the lamp 5 a is set as a reference (0degree), the AC supplied to the lamp 5 b uses a phase different from thereference phase by 120 degrees and the AC supplied to the lamp 5 c usesa phase different from the reference phase by 240 degrees. The lamps 5a, 5 b and 5 c are lit with ACs and irradiation light quantity waveforms9 a, 9 b and 9 c measured at the position of an object to be irradiated7 obtained when they are lit singly also fluctuate in a cycle double theAC frequency. The irradiation light quantity waveforms 9 b and 9 c havedifferent phases, but are waveforms substantially similar to that of theirradiation light quantity waveform 9 a. If the lamps 5 a, 5 b and 5 care turned ON simultaneously, since there are phase differences of 120degrees and 240 degrees among the ACs supplied to the three lamps 5 a, 5b and 5 c, an irradiation light quantity waveform 9 with substantiallyno temporal variation is obtained.

In Embodiment 3, the positional relationship between the object to beirradiated 7 and the three projectors 4 a, 4 b and 4 c and lamps 5 a, 5b and 5 c is assumed to be an equidistant and symmetric positionalrelationship. The three projectors 4 a, 4 b and 4 c are tilted towardthe object to be irradiated 7. As shown in FIG. 5, the three projectors4 a, 4 b and 4 c and lamps 5 a, 5 b and 5 c are arranged so as to belocated at vertices of a regular triangle. Moreover, the arrangement ismade in such a way that the irradiation light rays from the respectivelamps 5 a, 5 b and 5 c and projectors 4 a, 4 b and 4 c to the object tobe irradiated 7 are not blocked by their opposite projectors and lampsand other object. This makes the temporally averaged light quantitiesirradiated from the lamps 5 a, 5 b and 5 c substantially equal over theentire surface of the object to be irradiated 7 and even if the entiresurface of the object to be irradiated 7 is divided into smaller areasand measured, it is possible to obtain an irradiation light quantitywaveform 9 with substantially no temporal variation.

Furthermore, in order to set the temporal stability of irradiation lightquantity of the superimposed light to within ±10%, setting thearrangement of the optical system in such a way that the ratio of theamplitude of the irradiation light quantity waveform 9 a to theamplitudes of the irradiation light quantity waveforms 9 b and 9 cmeasured at the position of the object to be irradiated 7 when the lampsare lit singly is set to 1:0.75 to 1.33 as a standard can reduce thetotal adjustment load drastically and is therefore preferable.

Embodiment 4

FIG. 7 and FIG. 8 are schematic views of a method and apparatus forirradiating light according to fourth embodiment of the presentinvention. FIG. 7 is a schematic view showing a horizontal arrangementof a plurality of projectors and lamps according to Embodiment 4. FIG. 8is a schematic view of two sets of projector and lamp, which form abasic unit in FIG. 7. FIG. 9 is a graph showing a relationship betweenirradiation light quantity obtained right below the projector 4 a andlamp 5 a in FIG. 7 and FIG. 8. As in the case of Embodiment 1,Embodiment 4 also uses a metal halide lamp which is lit with an ACthrough an igniter as the light source.

In Embodiment 4 shown in FIG. 7, FIG. 8 and FIG. 9, power supplied froma primary side AC power supply of equipment 1 is supplied to lamps 5 aand 5 b in their respective projectors 4 a and 4 b through electricwirings 2 a and 2 b and igniters 3 a and 3 b. If the phase of the ACsupplied to the lamp 5 a is set as a reference (0 degree), the ACsupplied to the lamp 5 b uses a phase different from the reference phaseby 90 degrees. The lamps 5 a and 5 b are lit with ACs and irradiationlight quantity waveforms 9 a and 9 b measured at the positions rightbelow the projector 4 a and lamp 5 a obtained when they are lit singlyalso fluctuate in a cycle double the AC frequency. The irradiation lightquantity waveform 9 b has a different phase and amplitude, but it issubstantially similar to that of the irradiation light quantity waveform9 a.

In Embodiment 4, the positional relationship between a surface to beirradiated 10 and the two projectors 4 a and 4 b and lamps 5 a and 5 bis assumed to be an equidistant and symmetric positional relationship.The projectors 4 a and 4 b are oriented right below toward the surfaceto be irradiated 10. As shown in FIG. 7, the two closest basic units;projectors 4 a and 4 b and lamps 5 a and 5 b are arranged so as to belocated at vertices of a square. Furthermore, the arrangement is made sothat the irradiation light rays from the respective projectors 4 a and 4b and lamps 5 a and 5 b to the surface to be irradiated 10 are notblocked by their nearby projectors and lamps and other objects. This canmake the temporally averaged light quantities irradiated from the lamps5 a and 5 b substantially equal right below the projector 4 a and lamp 5a and near an intermediate position right below the projector 4 b andlamp 5 b. The light quantity right below one projector and lamp where alight quantity difference is likely to occur in this system is alsoappropriately adjusted by setting the distance between the projectors 4a and 4 b and between the lamps 5 a and 5 b, the distance from thesurface to be irradiated 10 in such a way that the ratio of theamplitude of the irradiation light quantity waveform 9 a to theamplitude of the irradiation light quantity waveform 9 b measured rightbelow the lamp 5 a when they are lit singly is substantially set to1:0.25. If all the lamps 5 a and 5 b are lit simultaneously in thiscondition, the irradiation light quantities from the closest fourprojectors 4 b and lamps 5 b which mainly contribute to the irradiationlight quantities surrounding the projector 4 a and lamp 5 a are added upeven right below the projector 4 a and lamp 5 a, and therefore, theamplitude of the irradiation light quantity waveform of the lamp 5 a issubstantially the same as that of a group of the closest lamps 5 b, thatis, the ratio is substantially 1:1, and because the phases of the ACsupplied to the lamps 5 a and 5 b are different from each other by 90degrees, an irradiation light quantity waveform 9 with substantially notemporal variation is obtained. This makes the temporally averaged lightquantities irradiated from the respective lamps 5 a and 5 bsubstantially equal over the entire area used of the surface to beirradiated 10 and even if the area used of the surface to be irradiated10 is divided into small areas and measured, it is possible to obtain anirradiation light quantity waveform 9 with substantially no temporalvariation.

Furthermore, in order to set the temporal stability of irradiation lightquantity of the superimposed light to within +10%, setting thearrangement of the optical system in such a way that the ratio of theamplitude of the irradiation light quantity waveform 9 a to theamplitude of the irradiation light quantity waveform 9 b measured atpositions right below the projector 4 a and lamp 5 a obtained when theyare lit singly is set to 1:0.21 (=0.25×0.82) to 0.30 (=0.25×1.22) as astandard can reduce the total adjustment load drastically, which istherefore preferable.

In this embodiment, a total of 15 sets of the projectors 4 a and 4 b andlamps 5 a and 5 b which are basic units are used, but expanding the samearrangement in FIG. 7 makes it possible to irradiate light ofirradiation light quantity with substantially no temporal variation overan arbitrary area. When a large object is irradiated with a largequantity of light, the number of light sources may be increased, butusing the present invention makes it possible to irradiate light inirradiation light quantity with substantially no temporal variation atsubstantially the same cost that would be required when the number oflight sources is simply increased. Using the present invention makes itpossible to carry out measurements of output of a large solar cellmodule or a photovoltaic array with a plurality of solar cell modulesconnected or characteristic tests such as an optical deterioration test.

Embodiment 5

FIG. 10 and FIG. 11 are schematic views of a method and apparatus forirradiating light according to fifth embodiment of the presentinvention. FIG. 10 is a schematic view showing a horizontal arrangementof a plurality of projectors and lamps according to Embodiment 5. FIG.11 is a schematic view of a set of three projectors and lamps, whichform basic units in FIG. 10. FIG. 12 is a graph showing a relationshipbetween irradiation light quantity obtained right below the projector 4a and lamp 5 a in FIG. 10 and FIG. 11 and time. As in the case ofEmbodiment 1, Embodiment 5 also uses a metal halide lamp which is litwith an AC through an igniter as the light source.

In Embodiment 5 shown in FIG. 10, FIG. 11 and FIG. 12, power suppliedfrom a primary side AC power supply of equipment 1 is supplied to lamps5 a, 5 b and 5 c in their respective projectors 4 a, 4 b and 4 c throughelectric wirings 2 a, 2 b and 2 c and igniters 3 a, 3 b and 3 c. Here, athree-phase AC is used as the primary side AC power supply of equipment1. If the phase of the AC supplied to the lamp 5 a is set as a reference(0 degree), the AC supplied to the lamp 5 b uses a phase different fromthe reference phase by 120 degrees and the AC supplied to the lamp 5 cuses a phase different from the reference phase by 240 degrees. Thelamps 5 a, 5 b and 5 c are lit with ACs and irradiation light quantitywaveforms 9 a, 9 b and 9 c measured at positions right below theprojector 5 a and lamp 5 a obtained when they are lit singly alsofluctuate in a cycle double the AC frequency. The irradiation lightquantity waveforms 9 b and 9 c have different phases and amplitudes, butthey are waveforms substantially similar to the irradiation lightquantity waveform 9 a.

In Embodiment 5, the positional relationship between a surface to beirradiated 10 and the three projectors 4 a, 4 b and 4 c and lamps 5 a, 5b and 5 c is assumed to be an equidistant and symmetric positionalrelationship. The projectors 4 a, 4 b and 4 c are oriented right belowtoward the surface to be irradiated 10. As shown in FIG. 10, the threeprojectors 4 a, 4 b and 4 c are arranged so as to be located at verticesof a regular triangle. Moreover, the arrangement is made in such a waythat the irradiation light rays from the respective projectors 4 a, 4 band 4 c and lamps 5 a, 5 b and 5 c to the surface to be irradiated 10are not blocked by nearby projectors and lamps and other objects. Thismakes the temporally averaged light quantities irradiated from the lamps5 a and 5 b substantially equal close to intermediate positions betweenpositions right below the projector 4 a and lamp 5 a, right below theprojector 4 b and lamp 5 b and right below the projector 4 c and lamp 5c. In this system, an appropriate adjustment is made by setting thedistances between the projectors 4 a, 4 b and 4 c and lamps 5 a, 5 b and5 c and the distance from the surface to be irradiated 10 even rightbelow any one projector and lamp, for example, right below the projector4 a and lamp 5 a in such a way that the ratio of the amplitude of theirradiation light quantity waveform 9 a to the amplitudes of theirradiation light quantity waveforms 9 b and 9 c measured at theposition right below the projector 4 a and lamp 5 a is substantially setto 1:0.33. If all the lamps 5 a, 5 b and 5 c are lit simultaneously inthis condition, irradiation light quantities from the three closestprojectors 4 a, 4 b and 4 c and lamp 5 a, 5 b and 5 c principallycontributing to the irradiation light quantities surrounding theprojector 4 a and lamp 5 a are added up even right below the projector 4a and lamp 5 a, and therefore, the amplitudes of the irradiation lightquantity waveforms from the group of projectors 4 a and lamps 5 a, thegroup of projectors 4 b and lamps 5 b and the group of projectors 4 cand lamps 5 c are also substantially the same, that is, the ratio is1:1:1, and because the phases of the ACs supplied to the lamps 5 a, 5 band 5 c are shifted by 120 degrees and 240 degrees, an irradiation lightquantity waveform 9 with substantially no temporal variation isobtained. In this way, the temporally averaged light quantitiesirradiated from the respective projectors 4 a, 4 b and 4 c and lamps 5a, 5 b and 5 c are substantially equal over the entire area used of thesurface to be irradiated 10, and even if the area used of the surface tobe irradiated 10 is divided into small areas and measured, it ispossible to obtain the irradiation light quantity waveform 9 withsubstantially no temporal variation.

Furthermore, in order to set the temporal stability of the irradiationlight quantity of the superimposed light to within ±10%, setting thearrangement of the optical system in such a way that the ratio of theamplitude of the irradiation light quantity waveform 9 a and theamplitudes of the irradiation light quantity waveforms 9 b and 9 cmeasured at positions right below the projector 4 a and lamp 5 aobtained when they are lit singly is set to 1:0.25 (=0.33×0.75) to 0.44(=0.33×1.33) as a standard can reduce the total adjustment loaddrastically, which is therefore preferable.

This embodiment has used a total of 12 sets of three projectors 4 a, 4 band 4 c and lamps 5 a, 5 b and 5 c which are basic units, but expandingthe same arrangement in FIG. 10 makes it possible to irradiate light inirradiation light quantity with substantially no temporal variation overan arbitrary area. When a large object to be irradiated is irradiatedwith a large quantity of light, the number of light sources may beincreased, but using the present invention makes it possible toirradiate light in irradiation light quantity with substantially notemporal variation at substantially the same cost that would be requiredwhen the number of light sources is simply increased. Using the presentinvention makes it possible to carry out measurements of output of alarge solar cell module or a photovoltaic array with a plurality ofsolar cell modules connected or characteristic tests such as an opticaldeterioration test.

Embodiment 6

FIG. 13 is a schematic view of a method and apparatus for irradiatinglight according to sixth embodiment of the present invention. FIG. 6 isa graph showing a relationship between irradiation light quantityobtained at the position of an object to be irradiated and time. As inthe case of Embodiment 1, Embodiment 6 also uses a metal halide lampwhich is lit with an AC through an igniter as the light source.

In Embodiment 6 shown in FIG. 13, power supplied from a primary side ACpower supply of equipment 1 is supplied to three lamps 5 a, 5 b and 5 cin one large projector 4 through electric wirings 2 a, 2 b and 2 c andigniters 3 a, 3 b and 3 c. Here, a three-phase AC is used as the primaryside AC power supply of equipment 1. If the phase of the AC supplied tothe lamp 5 a is set as a reference (0 degree), the AC supplied to thelamp 5 b uses a phase different from the reference phase by 120 degreesand the AC supplied to the lamp 5 c uses a phase different from thereference phase by 240 degrees. The lamps 5 a, 5 b and 5 c are lit withACs and irradiation light quantity waveforms 9 a, 9 b and 9 c measuredat the position of the object to be irradiated obtained when they arelit singly also fluctuate in a cycle double the AC frequency. Theirradiation light quantity waveforms 9 b and 9 c have different phases,but they are waveforms substantially similar to the irradiation lightquantity waveform 9 a. When the lamps 5 a, 5 b and 5 c are litsimultaneously, since the phases of the ACs supplied to the three lamps5 a, 5 b and 5 c are shifted by 120 degrees and 240 degrees, anirradiation light quantity waveform 9 with substantially no temporalvariation is obtained.

In Embodiment 6, the positional relationship between the object to beirradiated and the three lamps 5 a, 5 b and 5 c can be easily set to apositional relationship regarded as an equidistant and symmetric onebecause the three lamps 5 a, 5 b and 5 c are incorporated in oneprojector 4. The lamps 5 a, 5 b and 5 c are arranged so as to be locatedat vertices of a regular triangle in one projector 4. In this way,temporally averaged light quantities irradiated from one projector 4 andlamps 5 a, 5 b and 5 c are substantially equal over the entire surfaceof the object to be irradiated, and even if the entire surface of theobject to be irradiated is divided into small areas and measured, it ispossible to obtain an irradiation light quantity waveform 9 withsubstantially no temporal variation.

As described above, according to the present invention, an object to beirradiated is irradiated with simulated solar radiation resulting fromsuperimposed light rays from a plurality of light sources includinglight sources having different times at which light emission outputreaches a peak. Furthermore, the light irradiation apparatus used fortesting characteristics of a semiconductor device is a light irradiationapparatus characterized in that a semiconductor device is irradiatedwith light resulting from superimposed light rays from a plurality oflight sources including light sources having different times at whichlight emission output reaches a peak. Furthermore, the method of testingcharacteristics of a semiconductor device including a light irradiatingstep is a method of testing characteristics of a semiconductor deviceincluding a step of irradiating a semiconductor device with lightresulting from superimposed light rays from a plurality of light sourcesincluding light sources having different times at which light emissionoutput reaches a peak.

As a result, temporally stable light can be irradiated to an object tobe irradiated. Especially, simulated solar radiation, which needs to beirradiated in large light quantity and over a large area can beirradiated with light in temporally stable light quantity and spectrum.Furthermore, it is possible to irradiate a semiconductor device which isan object responding relatively quickly to a temporal variation in lightquantities over a sensitive wavelength range with temporally stablelight.

1. A method of irradiating an object with simulated solar radiationresulting from superimposed light rays from a plurality of light sourcesincluding light sources having different times at which light emissionoutput reaches a peak.
 2. The method of irradiating simulated solarradiation according to claim 1, wherein said light sources havingdifferent times at which the light emission output reaches a peak arelight sources including a plurality light-emitting seeds with differenttime constants.
 3. The method of irradiating simulated solar radiationaccording to claim 1, wherein said light sources having different timesat which the light emission output reaches a peak are discharge lamps.4. The method of irradiating simulated solar radiation according toclaim 3, wherein said discharge lamps are mercury lamps or metal halidelamps.
 5. The method of irradiating simulated solar radiation accordingto claim 1, wherein the output waveforms of said light sources havingdifferent times at which the light emission output reaches a peak aresubstantially similar.
 6. The method of irradiating simulated solarradiation according to claim 1, wherein the output waveforms of saidlight sources having different times at which the light emission outputreaches a peak are substantially periodic.
 7. The method of irradiatingsimulated solar radiation according to claim 1, wherein the energysupply sources of said light sources having different times at which thelight emission output reaches a peak are preferably a single-phase AC,two-phase AC or three-phase AC.
 8. The method of irradiating simulatedsolar radiation according to claim 1, wherein the phase difference oflight emission output peaks of said light sources having different timesat which the light emission output reaches a peak is an integer multipleof 1/n of 180 degrees, where n is the number of light sources or thenumber of light source groups having different times at which the lightemission output reaches a peak.
 9. The method of irradiating simulatedsolar radiation according to claim 1, wherein the arrangement of saidlight sources having different times at which the light emission outputreaches a peak includes an arrangement of m-gon, where m is an integermultiple of n and n is the number of light sources or the number oflight source groups having different times at which the light emissionoutput reaches a peak.
 10. The method of irradiating simulated solarradiation according to claim 1, wherein the arrangement of said lightsources having different times at which the light emission outputreaches a peak is linear.
 11. The method of irradiating simulated solarradiation according to claim 1, wherein the arrangement of said lightsources having different times at which the light emission outputreaches a peak is set in such a way that when the number of lightsources or the number of light source groups having different times atwhich the light emission output reaches a peak is 2, the ratio of a sumtotal of irradiation light quantities of light sources or light sourcegroups having different times at which one light emission output reachesa peak to a sum total of irradiation light quantities of light sourcesor light source groups having different times at which other lightemission outputs reach a peak is 0.82 to 1.22 as a standard for anobject to be irradiated.
 12. The method of irradiating simulated solarradiation according to claim 1, wherein the arrangement of said lightsources having different times at which the light emission outputreaches a peak is set in such a way that when the number of lightsources or the number of light source groups having different times atwhich the light emission output reaches a peak is 3, the ratio of a sumtotal of irradiation light quantities of light sources or light sourcegroups having different times at which one light emission output reachesa peak to a sum total of irradiation light quantities of light sourcesor light source groups having different times at which other lightemission outputs reach a peak is 1:0.75 to 1.33 as a standard for anobject to be irradiated.
 13. A light irradiation apparatus used fortesting characteristics of a semiconductor device, wherein saidsemiconductor device is irradiated with light resulting fromsuperimposed light rays from a plurality of light sources includinglight sources having different times at which the light emission outputreaches a peak.
 14. The light irradiation apparatus according to claim13, wherein said light sources having different times at which the lightemission output reaches a peak are light sources including a pluralitylight-emitting seeds with different time constants.
 15. The lightirradiation apparatus according to claim 13, wherein said light sourceshaving different times at which the light emission output reaches a peakare discharge lamps.
 16. The light irradiation apparatus according toclaim 15, wherein said discharge lamps are mercury lamps or metal halidelamps.
 17. The light irradiation apparatus according to claim 13,wherein the output waveforms of said light sources having differenttimes at which the light emission output reaches a peak aresubstantially similar.
 18. The light irradiation apparatus according toclaim 13, wherein the output waveforms of said light sources havingdifferent times at which the light emission output reaches a peak aresubstantially periodic.
 19. The light irradiation apparatus according toclaim 13, wherein energy supply sources of said light sources havingdifferent times at which the light emission output reaches a peak aresingle-phase AC, two-phase AC or three-phase AC.
 20. The lightirradiation apparatus according to claim 13, wherein the phasedifference of light emission output peaks of said light sources havingdifferent times at which the light emission output reaches a peak is aninteger multiple of 1/n of 180 degrees, where n is the number of lightsources or the number of light source groups having different times atwhich the light emission output reaches a peak.
 21. The lightirradiation apparatus according to claim 13, wherein the arrangement ofsaid light sources having different times at which the light emissionoutput reaches a peak includes an arrangement of m-gon, where m is aninteger multiple of n and n is the number of light sources or the numberof light source groups having different times at which the lightemission output reaches a peak.
 22. The light irradiation apparatusaccording to claim 13, wherein the arrangement of said light sourceshaving different times at which the light emission output reaches a peakis linear.
 23. The light irradiation apparatus according to claim 13,wherein the arrangement of said light sources having different times atwhich the light emission output reaches a peak is set in such a way thatwhen the number of light sources or the number of light source groupshaving different times at which light emission output reaches a peak is2, the ratio of a sum total of irradiation light quantities of lightsources or light source groups having different times at which one lightemission output reaches a peak to a sum total of irradiation lightquantities of light sources or light source groups having differenttimes at which other light emission outputs reach a peak is 0.82 to 1.22as a standard for an object to be irradiated.
 24. The light irradiationapparatus according to claim 13, wherein the arrangement of said lightsources having different times at which the light emission outputreaches a peak is set in such a way that when the number of lightsources or the number of light source groups having different times atwhich light emission output reaches a peak is 3, the ratio of a sumtotal of irradiation light quantities of light sources or light sourcegroups having different times at which one light emission output reachesa peak to a sum total of irradiation light quantities of light sourcesor light source groups having different times at which other lightemission outputs reach a peak is 1:0.75 to 1.33 as a standard for anobject to be irradiated.
 25. The light irradiation apparatus accordingto claim 13, wherein said semiconductor device is a solar cell.
 26. Amethod of testing characteristics of a semiconductor device with a lightirradiating step, comprising a step of irradiating the semiconductordevice with light resulting from superimposed light rays from aplurality of light sources including light sources with different timesat which light emission output reaches a peak.
 27. The characteristictesting method according to claim 26, wherein said light sources havingdifferent times at which the light emission output reaches a peak arelight sources including a plurality of light-emitting seeds withdifferent time constants.
 28. The characteristic testing methodaccording to claim 26, wherein said light sources having different timesat which the light emission output reaches a peak are discharge lamps.29. The characteristic testing method according to claim 28, whereinsaid discharge lamps are mercury lamps or metal halide lamps.
 30. Thecharacteristic testing method according to claim 26, wherein the outputwaveforms of said light sources having different times at which thelight emission output reaches a peak are substantially similar.
 31. Thecharacteristic testing method according to claim 26, wherein the outputwaveforms of said light sources having different times at which thelight emission output reaches a peak are substantially periodic.
 32. Thecharacteristic testing method according to claim 26, wherein energysupply sources of said light sources having different times at which thelight emission output reaches a peak are single-phase AC, two-phase ACor three-phase AC.
 33. The characteristic testing method according toclaim 26, wherein the phase difference of light emission output peaks ofsaid light sources having different times at which the light emissionoutput reaches a peak is an integer multiple of 1/n of 180 degrees,where n is the number of light sources or the number of light sourcegroups having different times at which light emission output reaches apeak.
 34. The characteristic testing method according to claim 26,wherein the arrangement of said light sources having different times atwhich the light emission output reaches a peak includes an arrangementof m-gon, where m is an integer multiple of n and n is the number oflight sources or the number of light source groups having differenttimes at which the light emission output reaches a peak.
 35. Thecharacteristic testing method according to claim 26, wherein thearrangement of said light sources having different times at which thelight emission output reaches a peak is linear.
 36. The characteristictesting method according to claim 26, wherein the arrangement of saidlight sources having different times at which the light emission outputreaches a peak is set in such a way that when the number of lightsources or the number of light source groups having different times atwhich light emission output reaches a peak is 2, the ratio of a sumtotal of irradiation light quantities of light sources or light sourcegroups having different times at which one light emission output reachesa peak to a sum total of irradiation light quantities of light sourcesor light source groups having different times at which other lightemission outputs reach a peak is 0.82 to 1.22 as a standard for anobject to be irradiated.
 37. The characteristic testing method accordingto claim 26, wherein the arrangement of said light sources havingdifferent times at which the light emission output reaches a peak is setin such a way that when the number of light sources or the number oflight source groups having different times at which light emissionoutput reaches a peak is 3, the ratio of a sum total of irradiationlight quantities of light sources or light source groups havingdifferent times at which one light emission output reaches a peak to asum total of irradiation light quantities of light sources or lightsource groups having different times at which other light emissionoutputs reach a peak is 1:0.75 to 1.33 as a standard for an object to beirradiated.
 38. The characteristic testing method according to claim 26,wherein said semiconductor device is a solar cell.